250 The Scottish Naturalist. 



relics of what were formerly rough uneven tors, projecting 

 bosses, and prominent rocks? The general tendency of glacial 

 action is to reduce the asperities of a land-surface ; hence pro- 

 jecting points are rounded off, while flat surfaces are simply, as 

 a rule, planed smoother. Mr Mackintosh might traverse acres 

 of such smoothed rock-surfaces in regions where the strata are 

 comparatively horizontal, — for example, in the case of the basal- 

 tic plateaux of the Faeroes and of Iceland, which have certainly 

 been glaciated by land-ice. Similar flat glaciated surfaces are 

 met with again and again both in the Highlands and Lowlands 

 of Scotland, occupying positions and associated with roches 

 moutonnces and till of such a character as to prove, beyond any 

 doubt, that they no less certainly are the result of the action of 

 land-ice. But it is needless to discuss the probability or possi- 

 bility of glaciation of any kind being due to floating ice. We 

 know that glaciers can and do polish and striate rock-surfaces; 

 no one, however, can say the same of icebergs : and until some 

 one can prove to us that icebergs have performed this feat, or 

 can furnish us with well-considered reasons for believing them 

 to be capable of it, glacialists will continue sceptical. 



But leaving these and other points which serve to show the 

 weakness of the cause which Mr Mackintosh supports with such 

 keen enthusiasm, I may, in conclusion, draw attention to cer- 

 tain very remarkable theoretical views of his which seem to me 

 to be not only self-contradictory, but opposed to well-known 

 natural laws. Briefly stated, his general view is that the erratics 

 of the west of England have been distributed by floating ice 

 during a period of submergence — the scattering of erratics and 

 the accumulation of the associated glacial deposits having com- 

 menced at or about the time when the land began to sink, and 

 continued until the submergence reached some 2000 feet below 

 the present sea-level. In applying this hypothesis to explain the 

 phenomena, Mr Mackintosh makes rather free use of sea-cur- 

 rents and winds. For example, he holds that a current coming 

 from Criffel carried with it boulder-laden ice which flowed south- 

 west to the Isle of Man, south to North Wales, and south-east 

 in the direction of Blackpool and Manchester, Liverpool and 

 Wolverhampton, Dawpool and Church Stretton. Now, in the 

 first place, it is very strange that there is not a vestige or trace 

 of any such submergence, either in the neighbourhood of Criffel 

 itself or in the region to the north of it. The whole of that 

 region has been striated and rubbed by land-ice coming down 



